Is there telephony now, independent of Internet channels?

Question

Telephony

Discussed in a small circle the feasibility of installing a fixed home phone. In case that if mobile communications suddenly fall in case of emergency, a landline phone will help out.
The opponent told me: there are no "landlines" in the sense in which you think. For a very long time. All traffic goes through the same channels.
Is there anything to say to him? To understand the situation. The question is not idle, I really want to put myself a home phone.
Thanks in advance.

Answer 1

well, on the one hand, indeed now all telephony goes through the Internet (but not quite through tcp / ip, but through the same channels, through e1 for example)
and on the other hand, a landline phone will still be more reliable if the Internet falls, because the telephony equipment obeys slightly different regulations and the operator is obliged to maintain its resilience in case of failures with more stringent requirements than ordinary Internet operators

Answer 2

Well, there is probably .. somewhere in the outback
But the channel from the automatic telephone exchange still goes through the Internet. Therefore, it can still be inside the PBX, but it’s already lying outside.
If mobile communications fall, there will be a wired Internet)